Less commonly recognized features of childhood nephrotic syndrome

IL-13-driven alterations in hepatic cholesterol handling contributes to hypercholesterolemia in a rat model of minimal change disease

Circulating factors have been implicated in the pathogenesis of minimal change disease (MCD), and may have direct effects on cholesterol metabolism. This study investigated the pathogenesis of hypercholesterolemia in an IL-13 overexpression rat model of MCD prior to the onset of proteinuria, so as to establish the direct contribution of IL-13, especially with regard to hepatic cholesterol handling. In this model of MCD, the temporal relationship between hypercholesterolemia and proteinuria was first identified. Plasma proprotein convertase subtilisin/kexin type 9 (Pcsk9) and liver ATP-binding cassette sub-family G member 5 (Abcg5) were measured using ELISA. Liver Ldlr and liver X receptor alpha (Lxra) were quantified with Western blot. Abcg5-mediated cholesterol efflux in IL-13-stimulated rat primary hepatocytes was measured using taurocholate as cholesterol acceptor. The role of Lxra was validated using a luciferase assay in Lxre-luciferase-transfected IL-13-stimulated hepatocytes. IL-13-transfected rats developed hypercholesterolemia prior to proteinuria, with 35% of rats hypercholesterolemic but only 11% proteinuric by Day 20 (P = 0.04). These pre-proteinuric hypercholesterolemic rats showed elevations in total and LDL-cholesterol, but not hypertriglyceridemia or hepatic steatosis. The hypercholesterolemia was associated with increased hepatic Pcsk9 synthesis and enhanced circulating Pcsk9 levels, which correlated strongly with plasma total cholesterol (r = 0.73, P<0.001). The hypercholesterolemia was also contributed by decreased Abcg5 expression and activity, due to reduced Lxra expression. Lxra expression correlated with plasma total cholesterol levels (r = −0.52, P = 0.01), and overexpression of pLxra in rat hepatocytes abrogated the IL-13-mediated down-regulation of Lxre-driven gene expression. In conclusion, we have shown that IL-13 induced changes in hepatic cholesterol handling in a cytokine-induced rat model of MCD, resulting in hypercholesterolemia which can precede the onset of proteinuria.

Hyperlipidemic profiles during remission in childhood idiopathic nephrotic syndrome

Hyperlipidemia, an important characteristic of idiopathic nephrotic syndrome in children (NS), is usually observed during the active phase of the disease and disappears with the resolution of the proteinuria. However, persisting lipid anomalies during remission have been reported in a few studies and raise the question of the later development of atherosclerosis. Plasma lipid profiles in 25 children with NS at remission, with or without active prednisone treatment, were compared with those of an age-matched population. The results indicate that plasma total and LDL-cholesterol levels were above the 95(th) percentile for age and sex in 12 of the 25 patients (48%) with 7 of them having apolipoprotein B and triglyceride concentrations above the 95(th) percentile. Moreover, frequently relapsing children were more likely to have abnormal lipid profile during the remission. We conclude that close monitoring of lipid levels during the remission of the NS especially in those with frequent relapses, is necessary to select the high-risk patients.

Persistent hypercholesterolaemia in frequently relapsing steroid-responsive nephrotic syndrome

OBJECTIVE

To investigate long-term changes of serum cholesterol levels in children with frequently relapsing steroid-responsive nephrotic syndrome (NS).

METHODOLOGY

Serum cholesterol values just before and during or immediately after 'relapse' were reviewed and the incidence of hypercholesterolaemia (> or = 200 mg/dL) was determined in eight patients (M:F, 6:2).

RESULTS

The patients with frequently relapsing NS usually showed hypercholesterolaemia (mean incidence, 81%) just before 'relapse' during clinical remission, as well as in relapse (mean incidence, 96%). A high incidence of steroid therapy was also found in each case (mean, 89%) just before relapse.

CONCLUSIONS

Our results demonstrate that children with frequently relapsing NS have prolonged periods of hypercholesterolaemia, even during clinical remission. It is suggested that serum lipid profiles be monitored carefully in such patients.

Hyperlipidemia in childhood nephrotic syndrome

Hyperlipidemia is an important characteristic of nephrotic syndrome (NS). Elevation of plasma total cholesterol, or more specifically low-density lipoprotein cholesterol, is the major lipid abnormality in NS, although hypertriglyceridemia may develop as the disorder progresses. The pathophysiology of nephrotic hyperlipidemia is complex. The prevailing view is that both hepatic synthesis of lipids and of apolipoproteins is increased, and that the clearance of chylomicrons and very low-density lipoproteins is reduced. The precise contribution of increased lipogenesis and decreased lipid catabolism to hyperlipidemia, and their relationship to urinary protein loss, hypoalbuminemia and reduced serum oncotic pressure remain controversial. There are two potential risks of elevated plasma lipids: atherosclerosis and progression of glomerular injury. Although neither of these complications has been proved with certainty, there is growing evidence that both may be long-term consequences of NS. Therefore, the diagnosis and treatment of lipid abnormalities, important aspects of the management of nephrotic children, is summarized here to provide pediatric nephrologists with an informed choice.

Treatment with a combination of low-density lipoprotein aphaeresis and pravastatin of a patient with drug-resistant nephrotic syndrome due to focal segmental glomerulosclerosis

Results of recent animal studies have lent support to the hypothesis that hyperlipidaemia may contribute to renal injury. This report documents the case of a 15-year-old boy with drug-resistant nephrotic syndrome due to focal segmental glomerulosclerosis (FGS) who showed an improvement in renal function and proteinuria as a result of treatment with low-density lipoprotein aphaeresis (LDL-A) combined with pravastatin. Although further work is required to determine the efficacy of lipid-lowering therapy in progressive glomerular disease in humans, the combination of LDL-A and pravastatin is likely be included in the choice of treatment modalities available for patients with drug-resistant nephrotic syndrome due to FGS.

Long-term follow-up in children with steroid-resistant nephrotic syndrome

A prospective study was performed in order to evaluate the efficacy of oral cyclophosphamide and chlorambucil in inducing a remission in children with steroid-resistant primary nephrotic syndrome (NS). Out of 215 children with steroid-resistant primary NS, 164 had been followed from one to 10 years. The children had a mean age of 8.2 years, with a range from one to 16 years. Steroid resistance was more common in children over six years of age compared with the other age groups. Hematuria was seen in 68 of the 164 children (41%); hypertension in 41 (25%); and hyperlipidemia in 112 (68%). Hypocomplementemia was noted in 24 of the 65 (37%) children in whom complement concentrations were determined. Renal biopsy was performed in 117 of the children. Pathologic changes consisted of minimal change nephrotic syndrome (MCNS) in 14 children (12%), membranoproliferative glomerulonephritis (MPGN) in 45 (38%), focal segmental glomerulosclerosis (FSGS) in 20 (25%), mesangial proliferation (MP) in 23 (20%), and membranous glomerulonephritis in six children (5%). Cyclophosphamide (2 mg/kg/day) was given to 164 patients, with complete remission and partial remission rates of 20.7% (34 of 164 children) and 24.4% (40 of 164 children), respectively. In this group, sustained remission and sustained partial remission rates were found in 20% (32 children) and 13% (21 children), respectively. Chlorambucil was given to 40 children with steroid- and cyclophosphamide-resistant nephrotic syndrome, with total remission and partial remission rates of 20% (eight children), and 12.5% (five children), respectively. These rates did not change during the follow-up. Thus, cyclophosphamide is valuable in the treatment of children with steroid-resistant NS with a variety of histologic changes.

Eruptive xanthomas in a child with the nephrotic syndrome

In a 4-year-old boy with steriod-resistant syndrome and extreme hyperlipidemia, an intense pruritic papular eruption developed on the trunk, buttocks, and extensor surface of the extremities. Findings from a skin biopsy specimen were consistent with an eruptive xanthoma. The patient was treated with gemfibrozil (Lopid), a low-fat diet, and antihistamines. Within 1 month pruritus diminished, the cutaneous lesions resolved, and serum lipid levels declined.